Johan Gerber is a shy, neat man with iron-grey hair, a ready smile and a quiet voice. But on the streets, he has taken to carrying an open pocket knife with a mean 10cm blade, concealed in an envelope and ready to use.

Last month, three men accosted him in broad daylight, one of whom hit him in the stomach and grabbed his mobile phone. A few years back, eight men surrounded him, held a knife to his throat and stole his wallet. His car and two trailers have also been stolen.

Gerber is afraid. In addition to the knife he carries when he is out on the street, he sells protection to many South Africans with the same fear: pistols and rifles, and hollow-point bullets that cause devastating injuries - the kind of bullets Olympic sprinter Oscar Pistorius used when he shot his girlfriend, Reeva Steenkamp, on Valentine's Day last year.

Pistorius, who is on trial for murder, was due to begin his defence yesterday. He has maintained in court statements that he mistook Steenkamp for an intruder when he fired four shots through a door, killing her as she cowered on the other side.

South Africa has been captivated by the trial, partly because of the celebrity status of Pistorius, the first athlete to compete in the Olympic Games on prosthetic devices, and his model girlfriend. There is a cable television channel dedicated to covering the case 24 hours a day, seven days a week. But some say there is another reason as well: South Africans' fear of crime.

The trial has helped launch a renewed debate in South Africa about an enduring problem: one of the highest rates of violent crime in the world, and its connection to race and economic opportunity.

Pistorius has said he was in a state of terror when he opened fire, believing that someone had broken into his house. He has not said whom he feared that someone was. He would not have to, according to crime novelist Margie Orford.

"The paranoid imaginings of suburban South Africa have lurked like a bogeyman at the periphery of this story for the past year," she wrote in a newspaper column on the eve of the trial. "It is the threatening body, nameless and faceless, of an armed and dangerous black intruder."

Raymond Suttner, a professor at Rhodes University, said in a blog post that "black" has always been "and continues to be, a code word for criminality in South Africa". Black South Africans counter that many who grew up during apartheid are equally fearful of violence by whites.

Some South Africans point to a lack of economic opportunity as the reason their country suffers such a high rate of violent crime. And Gerber says that half his customers are prosperous blacks, also seeking to protect themselves.

Twenty years after the end of apartheid, the country is still deeply unequal and divided.

This article appeared in the South China Morning Post print edition as: